Tag Archives: overactive amygdala

Open any newspaper, switch on any talk show on the radio this weekend, and you will be spoilt for choice with anxiety-inducing stories.

Living in this time of global recession, rising mortgage rates, political instability, it almost appears as if the media encourages us to be anxious on a daily basis.

Easy as it is to respond with anxiety to these stories, it is in fact the least productive response to have in life. It is like a mental pain we inflict on ourselves, clouding our judgment and reasoning, zapping us of the energy we need to move forward with our lives and make sound decisions. Anxious thoughts activate stress hormones that trigger the brain’s fight or flight response. But this arousal is temporary, and when it abates, is followed by exhaustion, apathy and even depression.

Not everyone is affected to the same degree by this tendency to react to life’s events with anxiety. We all know people who fret at the slightest thing, while others have the ability to remain calm and composed in the face of crisis. At its most chronic this tendency can lead to panic-attacks, social phobias, obsessive-compulsive behavior and post-traumatic stress disorder.

Now scientists at the University of California, Berkeley have discovered a neural explanation for why some individuals are indeed more anxiety-prone than others. Their findings, published in Neuron, reveal that chinks in our brain circuitry could be the answer, and may pave the way for more targeted treatment of chronic fear and anxiety disorders.

In the brain imaging study, the researchers discovered two distinct neural pathways that play a role in whether we develop and overcome fears. The first involves an overactive amygdala, which is home to the brain’s primal fight-or-flight reflex and plays a role in developing specific phobias.

The second involves activity in the ventral prefrontal cortex, a neural region that helps us to overcome our fears and worries. Some participants were able to mobilize their ventral prefrontal cortex to reduce their fear responses even while negative events were still occurring, the study found.

“This finding is important because it suggests some people may be able to use this ventral frontal part of the brain to regulate their fear responses – even in situations where stressful or dangerous events are ongoing”, said UC Berkeley psychologist Sonia Bishop, lead author of the paper.

“If we can train those individuals who are not naturally good at this to be able to do this, we may be able to help chronically anxious individuals as well as those who live in situations where they are exposed to dangerous or stressful situations over a long time frame,” Bishop added.

Bishop and her team used functional Magnetic Resonance Imaging (fMRI) to examine the brains of 23 healthy adults. As their brains were scanned, participants viewed various scenarios in which a virtual figure was seen in a computerized room. In one room, the figure would place his hands over his ears before a loud scream was sounded. But in another room, the gesture did not predict when the scream would occur. This placed volunteers in a sustained state of anticipation.

Participants who showed overactivity in the amygdala developed much stronger fear responses to gestures that predicted screams. A second entirely separate risk factor turned out to be failure to activate the ventral prefrontal cortex. Researchers found that participants who were able to activate this region were much more capable of decreasing their fear responses, even before the screams stopped.

The discovery that there is not one, but two routes in the brain circuitry that lead to heightened fear or anxiety is a key finding, the researchers said, and it offers hope for new targeted treatment approaches.

“Some individuals with anxiety disorders are helped more by cognitive therapies, while others are helped more by drug treatments,” Bishop said. “If we know which of these neural vulnerabilities a patient has, we may be able to predict what treatment is most likely to be of help.”